What kllrnohj says here. There are other trends as well. Because bandwidth was considered a very scarce resource, apps used to do very fine-grained dirty region

What kllrnohj says here. There are other trends as well. Because bandwidth was considered a very scarce resource, apps used to do very fine-grained dirty region tracking, and be very careful to update only what really changed (again, often by painting on the front buffer directly). Scrolling was often handled by an explicit bitblt operation, which commonly had hardware support even on very early computers. For complex reasons, that's all been changing. For example, Metal on macOS doesn't even have a way to specify partial screen updates. Those optimizations are still valid, though, and in my ideal world we have both good support for partial invalidation and fast GPU rendering. Among other things, that would be really good for power usage. But to get there requires some attention to detail that seems to be mostly gone from the desktop UI space.